In particular, but not limitedly, the invention regards the management of one or more feeders at a constant tension and/or speed and/or one or more control sensors for obtaining a product, which is obtained by means of a procedure generally divided into different and subsequent production steps, such as a stocking or any other product, a garment or similar textile product. Such products have portions (or “macro-areas,” such as the heel or the leg of a stocking) which are processed in specific and distinct operating phases during the production thereof. The invention also regards the management of a feeder or a sensor for controlling only one thread subjected to a particular treatment or processing (such as for example texturizing, winding, twisting, plying or the like).
Devices capable of feeding a thread to a textile machine maintaining the tension and/or speed of the thread constant and uniformed at a reference value called “setpoint” are known to the man skilled in the art. For example, in a machine like that for knitwear or production of stockings or production of ribbons, a plurality of threads is sent to the textile machine and such threads are fed by corresponding feeders of the aforementioned type.
During the production of numerous products (for example, but not limitedly, medical stockings, pantyhose, ribbons), there arises an ever-increasing need for modifying the setpoint value (regarding the tension and/or speed) of said feeder with the aim of obtaining, on a specific finished garment, a particular effect, as it occurs for example in graduated compression stockings or parts of the product (such as a stocking) having macro-areas with different characteristics (such as the heel or leg) or product parts with decorations (such as scarf or sweater).
It is also known that said setpoint value may even vary during the processing of only one thread or during one of the many processes required for producing the thread (such as twisting, winding, yarn clearing, intermingling or the like). For example, in the winding of a dyeing yarn it is important to maintain the winder loose and thus the tension with which the thread is wound should reduce as a function of the diameter thereof; or it is important to have a lower operating tension on the automatic doffing machine during the doffing step so as to facilitate the automatic winder change system.
In addition, it is known that the producers (or those processing the threads) have the need to manage the setpoint of the feeders as a function of the particular product meant to be obtained and thus the operating state of the textile machine or the particular operating step of the same in which a specific part of the product or a macro-area thereof is obtained. With particular, but not limited example to the stocking manufacturing industry, there arises the need of defining—for each macro-area of the stocking such as for example the cuff, leg, ankle, heel, foot, tip, (or any other product with parts obtained in a different manner such as for example swimming costumes, technical garments, ribbons with variable width, or the like)—the feeding tension and/or speed for each thread used for the implementation of the operating step during which such macro-area is obtained, but also only for the implementation of each operating step to obtain a specific part of a specific product being processed. There also arises the need to define the method (speed/ramp) through which one or the specific feeder device is required to pass from one setpoint to the other upon the variation of the production of various product macro-areas and/or the specific parts thereof.
In the present document, the term “macro-area” is used to indicate a portion of the product (such as for example the heel, leg or ankle in the stockings manufacturing industry). As regards the sensors for controlling the presence of the thread or controlling the quality of the latter, the need of activating the intervention only in some product production steps is known, i.e. during specific steps in which specific product macro-areas are obtained; in the case of stockings, for example, this applies for the obtainment of the leg or heel or any other portion of the stocking, or varying the operating and control parameters thereof as a function of the production steps of the various product macro-areas.
Various possible solutions, valid both in case of feeders at constant tension and feeders at constant speed, to this problem are currently known; thus, though the following examples refer to feeders at constant tension, they also apply in case of feeders at constant speed.
In a first known solution (EP0619261), many feeder devices provide for one or more digital inputs through which the modifications on the setpoint tension (the case of small or medium diameter circular machines mentions increases—INC—and decreases—DEC—or “graduations”) can be managed. In this case, the operator utilizes one or more digital outfeeds, normally present in the textile machines and freely programmable, with the aim of obtaining the specific desired products; such operator utilizes digital signals for modifying the reference value of each device in the operating program of the machine (the case of small and medium diameter circular machines mentions a “chain” machine, i.e. an assembly of commands and control that define the machine program).
However, such solution reveals numerous drawbacks. For example, the aforementioned known solution provides for the use of an increase digital outfeed and decrease digital outfeed by the machine for every device or groups of feeder devices associated thereto to allow the operator to program the setpoint of each device independently; thus, the solution requires a high number of programmable outfeeds of the machine, and this is not always possible. In addition, this solution implies that any modification, for example to the tension at which the thread is to be controlled during a particular process, implies the modification on the program of the machine to manage such programmable outfeeds in a different manner. For example, passing from a 2.0 grams tension to a 5.0 grams tension, with the increase/decrease resolution equivalent to 0.1 grams, shall require 30 increase pulses and thus at least 30 machine program lines; obviously, return to the initial 2.0 grams tension shall require 30 decrease pulses and other 30 lines of the machine program.
However, it should be observed that “old” textile machines and modern textile machines alike, are not always provided with freely programmable digital outfeeds; this for example creates problems during the “retrofit” step of the machines already available in the market even in the light of the fact that different wiring shall be required depending on the machine.
Another known solution is based on the fact that most feeders instead provide for a serial communication that is interfaced with the control unit, usually a microprocessor, of the textile machine, through which the reference setpoint value can be programmed to obtain various product macro-areas. Obviously, this solution is definitely more flexible with respect to the preceding one but it still reveals the following drawbacks:
the textile machine should already be predisposed for the serial management of said feeders. Thus, such solution is not applicable to all types of machines available in the market, in particular in case of application on machines of the old type;
such solution forces thread feeder manufacturers to closely collaborate with various manufacturers of textile machines, given that every device obviously has a specific communication protocol and depends on the communication standard required of the control unit of the textile machine;
thus, even this solution requires modifying the machine program any time one wants to modify the tension of a device in a particular area of the product.
Lastly, in case of improvements on the feeder device, for example increasing the resolution of the system or addition of new control functions, the new functions cannot be implemented on previously operating machines without requiring the intervention of the manufacturer of the latter to intervene on the software for managing the feeders.
EP2067886 reveals a system having the object of guaranteeing the quality of a finished textile product controlling the consumption of LFA (absorbed yarn length) of each feeder present on the textile machine, measuring the value thereof and thus making it coincide with the preset value, learnt or set by acting on the setting tension (setpoint) of the feeder. Basically, a control algorithm modifies the value of the operating tension of each feeder to keep the LFA value constant.
In order to operate in this manner, the known system provides for interfacing with the machine, though very simple, made up of a physical or virtual start signal (ZERO signal) and a periodical signal of the process progress state. In its simplest version, the system executes an LFA control and thus a change of tension of each feeder on each manufactured garment (end of cycle); in a more complex version instead, the control may occur at various points of the garment using the combination of two synchronization signals (end of cycle plus periodical signal) to define the processing point in a unique manner.
Thus, the system provides for a table in which the overall LFA values (set or learnt) at every instant of the production cycle of each feeder are recorded. These values are then subsequently used as reference for deciding how to modify the operating tension thereof as a function of the measured quantity.
US2008/256983 provides for a complex and direct synchronization of a plurality of thread feeders using a textile machine. The priority document has the object of providing a system capable of constantly communicating with the textile machine to receive—therefrom, information regarding the enabling and disabling of the single feeders, which would not be capable of feeding the thread to the textile machine in an independent and autonomous manner without these enabling and disabling signals. Such control system requires an absolute synchronization with the textile machine.
In this prior art text, the need for programming corrections regarding the feeders management signals with the aim of adapting the enabling and disabling signal thereof to make the system functional to the variation of the various types of thread for example, is mentioned on several occasions. The text describes advanced, lag or start signals at different feed speeds with respect to the actual ones with the aim of avoiding the stress of the thread, for example, during the start or stop steps. Thus, the feeders described in US 2008/256983 reveal their incapability to operate autonomously and thus the complexity of the system for managing these feeders upon the variation of the thread (for example yarn with different elasticity), upon the variation of the distance thereof from the point of insertion of the thread into the textile machine and upon variation of the types of machine.
US2008/256983 further describes the use of a tension sensor for activating and deactivating the single feeder devices; this with the aim obtaining a first reference map for enabling and disabling the feeders to be utilized subsequently, supplementing the data with the previously described advance and lag values.
Such known system reveals the considerable drawback lying in the fact that it has a learning/control step, during which the system is not under control. Such criticality is obviously even more limiting with reference to applications on large diameter circular machines (knitwear machine) wherein such step can be extremely long (reaching 30 minutes sometimes).
WO2013114174, on behalf of the applicant and to which the preambles of the independent claims of present document refer, describes a method and system for managing the feeding of a plurality of threads with constant tension and/or speed to a textile machine of the circular type, loom or yarn preparation. The threads are fed to said machine by a corresponding plurality of feeder devices; setting means adapted to set the operation thereof are connected thereto. The control means receive a synchronization signal—from the machine—regarding the start/end of the complete product processing cycle and a process progress state synchronization signal which, for example in the case of a circular machine, corresponds to the implementation of a complete or partial rotation (for example 4 pulses per rotation) of the cylinder of such machine. According to these signals, the setting means detect every operating step of a production cycle or the process progress state of a product or a production process. In the case of a circular loom, in particular, the aforementioned control means receive at least signals regarding the completion of a complete or partial rotation of the cylinder of such loom and according to the plurality of such signals, the production progress state of the product or the part of the product in question is established in an absolute and definite manner.
This prior art document provides for dividing such complete production cycle into different steps by means of corresponding synchronism signals (PRX) generated, for example in the case of a circular machine, by executing a complete or partial rotation of the relative cylinder. The control means intervene on each feeder device as a function of said steps (process progress state) or said synchronization signals so that such device feeds and/or controls the respective thread with predefined and peculiar tension and/or speed of each of such steps and thus each part of the product meant to be obtained. As a matter of fact, values of at least one characteristic of the thread fed by each feeder device selected from at least the tension, speed and presence of thread are set for each product production cycle corresponding to obtaining each part of the latter.
Such control means program such values of the aforementioned characteristics as a function of said steps whose actuation by the machine is defined and detected through the aforementioned synchronization signals continuously generated by said machine and received by said control means at each progress of the process.
WO2013114174 provides for that the values of each characteristic of the fed thread be recorded in a table in a memory of the control means so that each part of the produced product (defined by a synchronization signal PRX), for each complete or partial rotation of the cylindrical member of the machine and for every feeder device, there be provided a set data which can be used for comparing the corresponding current value detected by the interface, driving and control unit of the feeder device.
In the aforementioned table, the finished product is defined by a plurality of said signals having a series of numbers from 1 to N, where the signal PRX=N corresponds to the last part of the finished product or at the end of the production of the product. Thus, the Table is made up of as many production steps as the synchronization signals PRX; said steps define the lines of the aforementioned Table thus corresponding to different product production stages, i.e. the production of each part of the latter (precisely connected to each rotation of the cylinder, in the case of the circular textile machine, as indicated in page 9, lines 5-9 of WO2013/114174).
An example of the aforementioned Table is indicated below.
PRXAREAFEEDER TENSION 1FEEDER TENSION 21CUFF8.03.028.03.08.03.098.03.0108.03.011LEG6.04.0126.04.06.04.06.04.06.04.0496.04.0506.04.051HEEL4.03.04.03.0594.03.0604.03.061FOOT6.04.0626.04.06.04.06.04.0696.04.0706.04.071TIP4.03.04.03.04.03.0754.03.0764.03.0
The object of the prior art document in question is to provide a system that allows standardizing the production of a garment, by creating a table for example containing the trend of the setpoint tension of one or more feeders during the obtainment of each single part of the garment as a function of the process progress state. Thus, such tension corresponds to each single synchronization signal (or at least to a group of such signals continuously received from the control means and each necessarily corresponding to a production of a single part of the product).
In the prior art case in question, the tension to be used is the parameter that allows obtaining the garment with the desired characteristics. For example, in a graduated compression medical stocking, the table contains tension values to be used for obtaining the desired compression in the various parts or in the various points of the stocking (the compression potentially being different in the macro-area of the stocking defined by the ankle with respect to the compression present in the macro-area defined by the leg . . . ).
In addition, given that the interfacing with the machine is very simple and it does not absolutely depend on the model of the machine, manufacturer or technical characteristics thereof, the prior art document actually proposes an abstraction method that allows creating an article that is easy to transfer from one machine to the other. Besides not depending on the type of machine, such system also does not depend on the model of feeders used.
However, WO2013114174 provides for that each synchronization signal (for example generated by the machine for producing stockings at each rotation of the cylinder thereof) be used for controlling feeders or sensors. Thus, this subordinates such control to the actual obtainment of the synchronization signals and the plurality of such signals which corresponds to the length of each single part of the manufactured product or the length of each single operating step corresponding to said single part of the product. For example in the case of production of stockings of various sizes, different rotations of the cylinder have to be set for the same parts of the stockings as a function of the sizes thereof, said different settings leading to the production of different desired stockings. Thus, there arises the need for different programs for the same stocking hence obviously implying greater management complexity and probability of error by the operator.
For example, when producing the same type of stocking, but of different sizes, thus in which the number of synchronization signal PRX for each area is variable (for example, with reference to the Table above, 60 PRX are associated with the LEG instead of 40 PRX), the user is forced to modify the Table and thus always has to accurately know the PRX number associated to each area.
Thus, the invention of WO2013114174 still reveals a drawback in the application thereof in that, though at a lower extent, such application is always bound to the knowledge of the accurate duration (number of synchronization pulses PRX) of the single portions (macro-areas) of the product. In addition, in the solution provided for by WO2013/114174, the change of the macro-area of the product is associated to the PRX number (for example CUFF→LEG, associated to the passage of PRX from 10 to 11) and thus it varies as a function of the size; this necessarily requires different Tables for every size and the operator has to know and program the PRX range for each size (example SIZE_1 PRX from 10 to 11, SIZE 2 PRX 12 to 13, . . . ). Besides programming different Tables for every size, the operator also has to load different programs upon the variation of the size during the processing step. In addition, besides the discomfort and risk of error in loading erroneous programs, the implementation of WO2013/114174 implies considerably higher occupation of the memory of the control means.